1. Field of the Invention
The present invention relates to the design of sport boots, especially gliding sports, such as cross-country skiing or skating, or other sports, such as biking, in which the boot must be attached to the sport article while preserving a possibility of foot movement during the practice of the sport.
2. Description of Background and Material Information
In the aforementioned sports, and especially in cross-country skiing, different methods of fastening the boot to the sport article have been investigated.
Thus, the conventional binding method consists in attaching the boot to the cross-country ski by means of a stirrup cooperating with a front overlapping part of the sole and pressing this part against the cross-country ski.
Such a binding method prevents the complete movement of the foot since the foot is attached to an entire front part.
To overcome this drawback, different systems have been proposed to articulate the boot on the cross-country ski around an axle attached transversely to the boot.
Different positions of this axle, at the front of the boot, at the level of the metatarsal zones, etc., have been tested with a more or less degree of satisfaction.
The problem, in fact, is that while preserving a comfort of use, a compromise must be found between two completely contradictory requirements, namely:
a maximum movement or lifting of the foot, necessary for obtaining a great impulse or a wide stride, depending on the sport practiced, which implies a certain flexibility of the sole during bending, this flexibility varying according to the type of sport practiced; and
an optimum control and steering of the gliding member or sport article which, in theory, can only be obtained through a permanent xe2x80x9ccontactxe2x80x9d between the foot and the former, and/or a certain torsional rigidity of the sole, and therefore it is not compatible with a flexion or movement of the foot.
This problem was partially resolved in the document FR 2 739 788, which provides an assembly of a boot and a device for binding a boot to a sport article, in which the boot has two anchoring means constituted by transverse axles arranged, one at the front of the boot, and the other substantially in the area of the metatarsophalangeal articulation zone, and in which the binding device is provided so as to allow the rotation of the boot around the first anchoring axle and to exert a constant elastic return on the second anchoring axle in the direction of the sport article.
Thus, providing means for the elastic return of the boot towards the sport article, not at the front of the boot as in currently known devices, but at the rear of the binding devices of the boot, allows controlling the boot with respect to the gliding member even when the boot is raised.
Such a boot/binding system therefore allows reconciling the problems of lifting and control/steering of the boot with respect to the sport article, and therefore allows, in principle, an optimum movement of the foot.
The document FR 2 739 788 provides a positioning of the second transverse axle in the area of the metatarsophalangeal articulation zone.
However, experience shows that a positioning of such an axle right at the level of this articulation poses problems concerning comfort, since the flexion of the foot at this level occurs around a hard spot.
The positioning of the first axle is not obvious either. Indeed, the more this axis is positioned towards the front, the greater the clearance, but if this axle is arranged too far towards the front, the movement of the foot will be hindered since the athlete will not have the feeling of a pure rotation.
On the other hand, the movement will not be optimum either if the first axle is placed too far back with respect to the end portion of the boot.
An object of the present invention, therefore, is to overcome the aforementioned drawbacks and to propose a sole for a sport boot that reconciles the requirements for control movement/foot steering without having a negative effect on comfort.
This object is achieved in the sport boot sole according to the invention which is of the type having, on its lower surface, two connecting members offset one with respect to the other in the longitudinal direction of the boot and arranged substantially transversely, whereby the first connecting member is arranged in the area of the front end portion, and the second connecting member is arranged behind the first connecting member, and substantially in front of the metatarsophalangeal articulation zone.
Indeed, it is guaranteed through this arrangement that the second connecting member will only operate at the end of a rolling movement on the metatarsophalangeal articulation; consequently, it will not hinder this movement.
According to a preferred embodiment, the first connecting member is arranged in the area of the front end portion of the toes or right in front of this end portion.
Such an arrangement also allows guaranteeing a rolling movement on the toes without the presence of hard spots.